As is described in U.S. Pat. Nos. 3,317,322 and 3,761,276, it is known that reversal images can be obtained by direct reversal processing comprising developing in the presence of a fogging agent or exposing the total element surface at development, when the surface of internal latent image silver halide particles, which comprises a core of silver halide which is doped with metal ions and/or subjected to chemical sensitization and shell of silver halide which covers at least the sensitive sites of said core (hereinafter, referred to as core/shell particles), are chemically sensitized.
However, chemically sensitized neclei obtained by chemically sensitizing the surface of such internal latent image core/shell silver halide particles have the drawback that reversal photographic properties such as D.sub.max sensitivity or gradation, etc., deteriorate when they are stored for long periods of time or left in a severe environment such as at high temperature and high humidity, etc., because tney have poor stability with the passage of time.